<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <div id="wrap"></div>

    <script>
        
        /*
        新的API,低版本浏览器不支持

        */

        let oWrap = document.getElementById("#wrap");
        console.log(oWrap.classList);
        
    </script>
</body>
</html>